Fixing arrangement

ABSTRACT

Method and apparatus for affixing electroscopic toner images onto a support in which a quantity of particulate material is heated to a temperature sufficient to produce at least a partial melting of the particular toner material to be fused and the toner material on the support is then contacted with the heated particulate material to induce a transfer of the thermal energy in the particulate material to the toner material on the support.

United States Patent Inventor Robert H. Detig Old Tappan, NJ. Appl. No.872,558 Filed Oct. 30, 1969 Patented Nov. 30, 1971 Assignee XeroxCorporation Rochester, N.Y.

FIXING ARRANGEMENT 2 Claims, 2 Drawing Figs.

U.S. Cl Int. Cl

Field of Search G03gl5/20 263/6 R, 6 E; 34/57 R, 57 A [56] ReferencesCited UNITED STATES PATENTS 2,726,166 [2/1955 Greaves 263/6 E UX3,448,970 6/1969 Kolibas 263/6 E X Primary Examiner-Charles J. MyhreAttorneys-Paul M. Enlow, James J. Ralabate, Ronald Zibelli and Terry J.Anderson ABSTRACT: Method and apparatus for affixing electroscopic tonerimages onto a support in which a quantity of particulate material isheated to a temperature sufficient to produce at least a partial meltingof the particular toner material to be fused and the toner material onthe support is then contacted with the heated particulate material toinduce a transfer ofthe thermal energy in the particulate material tothe toner material on the support.

PATENTED NUVSOIHYI 34623710 FIG. 2

u 53mm 1 R\\ L\ \l INVENTOR. ROBERT H. DETIG FIXING ARRANGEMENTBACKGROUND OF THE INVENTION This invention relates generally to theafiixing of electroscopic toner material to a support member and moreparticularly to permanently affixing electroscopic toner material in animage configuration onto a support by the use of heat.

In order to permanently affix an electroscopic toner material onto asupport member by heat, it is necessary to elevate the temperature ofthe electroscopic toner material to a point at which at least one of theconstituents of the toner material is caused to melt. This action causesmolten droplets of the toner material to form which molten droplets areabsorbed to some extent in the fibers of the support member which inmany instances constitutes paper so as to produce a permanent affixationof the toner material on the support. Thereafter, as the toner materialis cooled, solidification of the toner material occurs causing the tonermaterial to be firmly bonded to the support material.

In both the electrographic recording art as well as the xerographic art,the use of heat for fixing toner images onto a support is old and wellknown. For example, one of the oldest and perhaps the most commonheat-fixing or fusing arrangements heretofore, has been the use of aresistance heating element which is supported in a reflecting deviceadjacent the support material. However, since in most such applications,the support material generally constitutes paper, such radiant-heatingdevices have had an adverse affect on the support material itself. Thatis, in such fixing arrangements in order to insure sufficient fusion ofthe toner material to the paper, the temperature therein has been suchas to elevate the temperature of the paper as well as the toner beyond apoint so as to have deleterious effects on the paper. For example, inmost radiantfusing devices, not only is the temperature of the tonermaterial in image configuration elevated, the temperature of the papersupport also is elevated which has the effect of evaporating and hencereducing the moisture content normally present within the papermaterial. This has the adverse affect of causing the affect of causingthe paper to become brittle, as well as warping or inducing a curltherein. Accordingly, such radiant-fusing arrangements have heretoforebeen found generally unacceptable in many applications.

Another problem involved in both electrographically fonnerl images aswell as xerographically formed images, has been the obtaining of optimumquality reproductions. In the electrographic recording process whereinlatent electrostatic images are deposited directly onto a dielectricmaterial such as paper, which images are thereafter developed with anelec troscopic toner material and in the xerographic process wherein alatent electrostatic image is formed on a photoconductive insulatingmaterial and then developed with an electroscopic toner material, thedeveloped images thereafter being transferred to a support material suchas paper, unwanted, scattered depositions of toner material are obtainedin nonimage areas of the reproduction. While this difficulty maygenerally be attributed to deficiencies in the particular developmentsystem, the problem nevertheless exists, resulting in a reproductionhaving scattered depositions of unwanted toner particles in backgroundof nonimage areas along with the wanted larger deposits of tonermaterial in the image areas of the reproduction.

It should therefore be appreciated that prior to fusing, all the tonermaterial including that comprising the wanted image areas as well as theunwanted background areas is loosely held, posing a difficult problem ofselectively removing the unwanted background areas without adverselyaffecting the wanted image areas. At the same time, following fusing inthe known fusing devices, all the powder has heretofore been permanently'affixed thereto so as to render the problem of selective removal of thebackground areas impossible. Efforts to remove this unwanted backgrounddeposition have heretofore generally been unsuccessful and accordinglythe need to effect the elimination thereof has long been recognized.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide improved method andapparatus for afiixingelectroscopic toner material onto a support member.

It is a further object of the present invention to provide improvedmethod and apparatus for permanently affixing electroscopic tonermaterial onto a support member by the use of heat without adverselyaffecting the support material.

It is still another object of the present invention to provide methodand apparatus for producing permanently afiixed electroscopic tonermaterials on a support in image configuration which are devoid ofscattered toner particles in the background nonimage areas.

It is still a further object of the present invention to provide methodand apparatus for permanently affixing a loose electroscopic powderimage onto a support member without producing an affixation of unwantedscattered particles of developer material in the background nonimageareas.

These and other objects of the invention are attained by heating aquantity of particulate material to a temperature sufficient to produceat least a partial melting of the particular toner material to be fused,and contacting the toner material on the support with the heatedparticulate material to induce a transfer of the thermal energy in theparticulate material to the toner material on the support.

Other objects of the invention will become readily apparent to thoseskilled in the art in view of the following detailed disclosure anddescription thereof, especially when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration ofa system in which the fusing arrangement as contemplated by the presentinvention is particularly adapted for use.

FIG. 2 is an enlarged schematic illustration of the fusing arrangementillustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the presentinvention electroscopic toner images which are to be permanently affixedto a support such as paper are contacted with a quantity of particulatematerial heated to a temperature sufficient to produce at least apartial melting of the toner material, which upon contact induces atransfer of the thermal energy in the particulate material to the tonermaterial. As at least a partial melting of the toner images is thusproduced, the melted toner material flows to a certain extent into thefibers of the support material which after cooling readily adheres in apermanent manner to the support material.

Although the invention will be described with particular reference totoner images which are formed through the now well-known xerographicprocess, it will be readily appreciated by those skilled in the art thatthe fusing arrangement as contemplated by the present invention is alsoreadily adaptable for permanently affixing electroscopic toner imagesonto a support which have been produced by means of an electrographicrecording or electrostatic printing process.

, Referring to FIG. I, in which a xerographic reproducing apparatus hasbeen schematically illustrated, an original copy to be reproduced isplaced on a supporttray 10 from which it is fed into a feed apparatusgenerally designated I 1. On the feed apparatus the original is moved onan endless belt 12 driven by motor 13 to pass the optical axis ofprojection lens system 14 that is illuminated by a projection lampLMP-l. The image of the original is reflected by mirror 15 through anadjustable objective lens 16 and then reflected by mirror 17 downwardlythrough a variable slit aperture assembly I8 and onto the surface of axerographic plate in the form of a drum l9.

Xerographic drum 19 includes a cylindrical member mounted in suitablebearings in the frame of the machine and is driven in a clockwisedirection by a motor 24 at a constant rate that is proportional to thetransport rate of the original,

whereby the peripheral rate of the drum surface is identical to the rateof movement of the projected radiation image. The drum surface comprisesa layer of photoconductive material on a conductive backing that issensitized to exposure by means of a corona-generating device 25 whichmay be an adaption of the type disclosed in Vyverberg US. Pat. No.2,836,725 that is energized from a suitable high potential source.

The exposure of the drum to the radiation image discharges thephotoconductive layer in the areas struck by radiation, whereby thereremains on the drum a latent electrostatic image in image configurationcorresponding to the radiation image projected from the original. As thedrum surface continues its movement, the electrostatic latent imagepasses through a developing station 26 in which a two-componentdeveloper material 27 which may be of the type disclosed in Walkup, US.Pat. No. 2,638,416, is cascaded over the drum surface by means ofdeveloping apparatus 28.

In the developing apparatus, developing material is carried up theconveyor 29, driven by suitable drive means from the motor 30, and thenreleased onto chute 31 whereby it is cascaded down over the drumsurface. The toner component 32 of the developer that is consumed indeveloping is stored in dispenser 33 and is dispensed in amountscontrolled by gate 34.

After developing, the xerographic powder image passes a dischargestation 41 at which the drum surface is illuminated by lamp LMP-2,whereby residual charges on the nonimage areas of the drum surface arecompletely discharged. Thereafter, the powder image passes through animage transfer station 42 at which the powder image is electrostaticallytransferred to a moving support surface 43 by means of a secondcorona-generating device 44 similar to corona-charging device 25,mentioned above.

The moving-support surface 43 to which the powder image is transferredmay be of any convenient type, such as paper, and may be obtained from asupply roll 45, fed over guide roll 46 and over suitable tensioningrolls being directed into surface contact with the drum in the immediatevicinity of transfer corona-generating device 44. After transfer, thesupport surface 43 is separated from the drum surface and guided throughthe fusing apparatus as contemplated by the present invention generallydesignated 48, wherein the powder image is permanently affixed thereto.Thereafter, the support surface may be fed over a further system ofguide and tensioning rolls and onto a takeup roll 52 that is driven bymotor 53.

After separation of the support surface 43 from the drum, acorona-generating device 54 directs electrostatic charge to a residualpowder image on the drum surface. Thereafter, the xerographic drumsurface passes through a cleaning station 55 at which the surfacethereof is brushed by a cleaning brush assembly 56, rotated by a motor57, whereby residual developing material remaining on the drum surfaceis removed. The drum surface then passes through a second dischargestation 58 at which it is illuminated by fluorescent lamp LMP-3, wherebythe drum surface in this region is completely flooded with light toremove any electrostatic charge that may remain thereon. Suitable lighttraps are provided in the system to prevent any light rays from reachingthe drum surface, other than the projected image, during the period ofdrum travel immediately prior to sensitization by corona-generatingdevice 25 until after the drum surface has completely passed through thedeveloping station 26.

During operation of the xerographic apparatus, the image bearing supportsurface 43 carrying the loose powder images 90 is moved through thefusing apparatus in a path accorded by the interrelation of rollers 62,63 and 64. While the support material 43 with the toner images 90thereon has been shown and described as being in the form of anelongated web it will be appreciated by those skilled in the art thatthe fusing arrangement as contemplated by the present invention isequally applicable to the use of support materials in the form ofcutsheet stock.

The fusing apparatus 48 includes a container 67 which is open at theupper end thereof to permit the image-bearing support surface 43carrying the loose powder images thereon into proximity with the fusingapparatus.

A plenum 68 is connected at the bottom of container 67 for a purposewhich will hereinafter more readily be apparent. A wall or floor 69 atthe bottom of container 67 forms a partition between the container 67and plenum 68. Floor 69 includes a plurality of openings 69' thereinwhich permit the passage of a pressurized gas from plenum 68 throughopenings 69' into container 67. it should be noted however, that thesize of openings 69 in FIGS. 1 and 2 of the drawings have beenexaggerated for purposes of clarity and in actual practice are of aquite small dimension of a microporosity nature.

A heating element 70 is located within container 67 adjacent wall 69.Heating element 70 may comprise a resistance heating element of the typewhich is generally well known. That is, that type of heating elementwhich produces a generation of heat therefrom upon the passage of anelectrical current through suitable conductors. Accordingly, heatingelement 70 is electrically connected to a source of electrical potentialwhich when activated produces a heating of element 70 within container67. Suitable control means may be provided in conjunction with heatingelement 70 to control or vary the quantity of heat generated by heatingelement 70.

Fusing apparatus 48 includes a quantity of particulate material 71 whichis supported and contained within container 67. Particulate material 71may comprise a variety of materials which are capable of absorbing andradiating heat. Among those materials which have been found to workparticularly well are sand particles, glass beans, and metal filings orchips. Additional materials in the form of particles which readilyabsorb and radiate heat may also be utilized in accordance with thepresent invention.

A brush-cleaning arrangement 65 is positioned to contact supportmaterial 43 with the images 90 thereon after the support material 43 haspassed from fuser 48. Brushes 65 are rotated by means of a motor 66 toremove any of the particulate material 71 which may be loosely adheringto support material 43 after passing through fusing apparatus 48. Inaddition, brush-cleaning arrangement 65 may also remove any looselyadhering toner particles on support 43 as well as any of the particulatematerial 71 which may inadvertently adhere to the support material 43after passing through fusing apparatus In operation, with heatingelement 70 activated by means of suitable electrical circuitry, heat isgenerated within container 67 and radiated from heating element 70. Asheat is thus generated by heating element 70 the particulate material 71within container 67 absorbs heat generated by heating element 70. As hasbeen previously mentioned, the quantity of heat generated by heatingelement 70 may be regulated to the extent so as to impart a sufficientquantity of heat to the particulate material 71 to at least partiallymelt the toner material in the image configuration 90 so as to fuse andpermanently adhere to support 43.

With particulate material 71 being thus heated by heating element 70, agas such as air for example, is introduced under pressure into plenum68. As the pressurized air thus enters plenum 68, it passes through themicroporous openings 69' in wall 69 to cause a random movement of theindividual particles comprising particulate material 71 throughout theconfines of container 67. As movement of the individual particlescomprising particulate material 71 is thus introduced, the particulatematerial 71 assumes the form of a moving fluid within container 67passing over the exposed surface of support 43 'within container 67. Asthe particulate material 71 is thus fluidized it contacts the surface ofweb 43 with images 90 thereon to effect the fusing operation.

In the dominant image areas 90, as the particulate material comes incontact therewith, heat is conducted from the individual particles whichcomprise particulate material 71, as heat is thus conducted to'the tonerimages a melting of the toner images is produced fusing the toner imagesonto support 43. In the nonimage or background areas, where individualparticles of the particulate material 71 contact support 43, little orno heat is conducted to support 43. This is due in large part to thefact that the support itself is a poor heat conductor and in these thereis an absence of substantial quantities of toner particles thereat.Hence little or no heat is transferred to support 43, in the nonimage orbackground areas.

As particulate material 71 contacts support 43 the particulate material71 has the additional feature of producing an abrasive action againstsupport 43. This abrasive action exerted by the particulate material 71against support 43 in the toner image areas 90 has little or no effectupon removing the toner images 90 from the support 43 because of thegood heat transfer characteristics exhibited between the particulatematerial 71 contacting toner images 90. However, in the nonimage areason support 43, the fluidized particulate material 71 produces asufficient abrasive action against support 43 to remove unwanteddeposits of toner particles from support 43. This is believed to resultfrom the fact that these small background areas are much less receptiveto the absorbency of heat than the more dense image areas 90. However,for whatever reason, the fact remains that the image areas are fused tosupport 43 whereas the nonimage areas remain unfused and are removedfrom support 43 by the abrasive action of particulate material 71.

ln the preferred arrangement, sand granules may comprise the particulatematerial 71. However, as has been indicated, other suitable materialswhich readily absorb and conduct heat may also be utilized as theparticulate material 71.

It should also be appreciated that a fluidization of the particulatematerial 71 within container 67 may be produced by means other thanthrough the use of plenum 68 and the introduction of a compressed gassuch as air. For example, a sonic transducer may be attached tocontainer 67 which upon activation thereof produces a fluidization ofparticulate material 71 within container 67 in much the same manner asdoes the introduction of compressed gases through plenum 68.

While the invention has been described with reference to a preferredarrangement it will be generally understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the true spirit and scope of theinvention.

What is claimed is:

1. Apparatus for affixing electroscopic toner images onto a supportcomprising,

a reservoir containing a quantity of particulate heat absorbentmaterial,

a heating element operatively disposed within said reservoir and adaptedwhen activated to produce a heating of said particulate material withinsaid reservoir,

means for passing a support having unfused electroscopic toner imagesthereon proximate to said reservoir, and

means for producing a fluidized movement of the heated particulatematerial within said reservoir to contact the unfused electroscopictoner images on said support to produce at least a partial melting ofsaid toner images.

2. Apparatus for permanently affixing electroscopic toner images onto asupport comprising,

a reservoir containing a quantity of particulate heat absorbentmaterial,

a heating element operatively disposed within said reservoir and adaptedwhen activated to produce a heating of said particulate material withinsaid reservoir,

means for passing a support having unfused electroscopic toner imagesthereon proximate to said reservoir,

a source of pressurized gas,

means for conducting said pressurized gas from said source into saidreservoir to generate a fluidized movement of said heated particulatematerial therein, said fluidized movement contacting said heatedparticulate material with the toner images on said support to produce atleast a partial melting of said toner images on said support.

1. Apparatus for affixing electroscopic toner images onto a supportcomprising, a reservoir containing a quantity of particulate heatabsorbent material, a heating element operatively disposed within saidreservoir and adapted when activated to produce a heating of saidparticulate material within said reservoir, means for passing a supporthaving unfused electroscopic toner images thereon proximate to saidreservoir, and means for producing a fluidized movement of the heatedparticulate material within said reservoir to contact the unfusedelectroscopic toner images on said support to produce at least a partialmelting of said toner images.
 2. Apparatus for permanently affixingelectroscopic toner images onto a support comprising, a reservoircontaining a quantity of particulate heat absorbent material, a heatingelement operatively disposed within said reservoir and adapted whenactivated to produce a heating of said particulate material within saidreservoir, means for passing a support having unfused electroscopictoner images thereon proximate to said reservoir, a source ofpressurized gas, means for conducting said pressurized gas from saidsource into said reservoir to generate a fluidized movement of saidheated particulate material therein, said fluidized movement contactingsaid heated particulate material with the toner images on said supportto produce at least a partial melting of said toner images on saidsupport.